does it make a noticeable difference with the cans sealed completely like that? in other words, is it worth the work?

Sure it is. Look at it this why. You have to compress and rarify the air molecules within the pod to the same degree as you do external to the speaker midbass cone. In other words, the internal displacement has to match the external displacement. But since the pod is so small, this creates far more internal pressure than the external open air. With that much pressure it only takes a very small leak. If those positive and negative pressures are allowed to escape the pod then those waveforms are opposite (inverted) of the speakers's external radiation which causes direct cancellations below frequencies (wavelengths) that are longer half this distance. This condition also serves to undermine any damping of the speaker (not only the air springyness of the trapped air in the pod but the natural resistance of open air. So, there goes the midbass, control, SQ, and your power handling.
In an IB coaming speaker you do not need a small pod since the speaker is intended for this type of expansive cavity. This type of speaker is self-damped to a greater degree and less dependent on the air spring of trapped air for control. But you still must have the front to rear acoustic isolation.